OK, it's a basic rule of business: Go where the customers are. And in some places in the world, those customers are stuck in their cars on the roads, in the middle of traffic jams. Robert Smith, from NPR's Planet Money team, was recently in Jakarta, Indonesia. It has some of the worst traffic on the planet; and Robert noticed that when the cars slow down, the entrepreneurs come out.

(SOUNDBITE OF TRAFFIC NOISES)

ROBERT SMITH, BYLINE: I am standing in the middle of a Jakarta traffic jam, and I'm not the only one here without a car. Over on the left, there's a guy pushing his chicken cart into traffic, clanging his pots. And then right down the center lane, there are these guys carrying stacks and stacks of nuts and treats, and crackers as big as your head; and they're all trying to get the attention of the drivers.

There is a whole world of commerce inside a Jakarta traffic jam, and the shrewdest businessmen that I met were the teenage boys. You see them at the intersections, standing in sandals and T-shirts, and they are directing traffic - for a price. If you want to merge or, say, turn across three lanes of cars, you signal to the boys; and then they go out into traffic, and make room for you.

It's amazing because they're such skinny, little teenagers that they sometimes fit in between trucks that are maybe a foot apart, and this guy brought his own whistle. When you're through, you toss them a few coins - five cents, 10 cents. I managed to get close enough to one of them. He's 12 years old - Amir. And I asked him, how much money do you make?

AMIR: (Speaking foreign language)

UNIDENTIFIED INTERPRETER: About $7.

SMITH: Seven dollars a day - that's an enormous sum for a kid in Indonesia. Now, the government of Jakarta knows that it looks bad when some of its traffic cops are really 12-year-olds working for tips. So the city is working on some traffic solutions. They've built carpool lanes in the center of the city - hasn't actually done much to ease traffic, but it has created a whole new kind of business.

I met a woman. Her name is Ea-Ease(ph), 23 years old, and she stands on the road just before the carpool lanes, holding up this adorable toddler.

EE-EASE: (Through interpreter) This is my daughter, Selfe. She is 2 years old.

SMITH: And the kid is a clever bit of marketing. The mom explains to me that if a driver pays her $2, she and the kid will get in the passenger seat. Three people gets you into the carpool lane. And she tells me the baby counts.

EE-EASE: (Speaking foreign language) (Laughter)

SMITH: On some stretches of road you can see a dozen women all in a row, all carrying babies, waving three fingers - that's the sign - at all the single drivers they see. Now, all these entrepreneurs make traffic more bearable, but only one businessman out there can actually get me out of this traffic jam. That's the Ojek driver. An Ojek is a guy with a motorcycle waiting on the side of the road.

For a dollar or so, you can hop on the back of a motorcycle; and the guy will speed his Ojek through the tiny spaces in between the cars.

UNIDENTIFIED MAN #2: This Ojek is very quickly.

SMITH: Very fast.

UNIDENTIFIED MAN #2: Very fast.

SMITH: All right. Let's do this thing. Let's go!

There is no helmet offered. You just hold on tight, and it is terrifying. But I gotta say, fastest we've moved all day. On the traffic-clogged streets of Jakarta, I'm Robert Smith, NPR News.

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